Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image of a first embodiment in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the first image of a second embodiment in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 7 is the second image thereof;

FIG. 8 is the third image thereof;

FIG. 9 is the fourth image thereof; and,

FIG. 10 is the fifth image thereof.

The outermost broken line in the figures depicting the display screen or portion thereof is for environmental purposes only and forms no part of the claimed design.

The remaining broken lines in the figures depict portions of the display screen or portion thereof with transitional graphical user interface which form no part of the claimed design.

The appearance of the graphical user interface sequentially transitions between the images shown in FIGS. 1-5 and in FIGS. 6-10. The process or period in which one image transitions to another forms no part of the claimed design. 

CLAIM We claim the ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 